The sum rule (REF ) depends on the various vacuum condensates
written down above (REF ). It contains the masses and decay
constants of the final-state mesons \(D^-\)  and \(K^+\) : relevant spectroscopic
parameters are collected in Table REF . All of them are borrowed
from Ref. [1]}. For decay constants \(f_D\)  and \(f_K\) 
Particle Data Group's averages are used.
